The invention relates to transcranial magnetic stimulation (TMS), and more particularly relates to TMS coils. In its most immediate sense, the invention relates to securing a TMS coil to a patient's head.
In TMS, a current pulse (or a series of current pulses) is directed through a coil (a “TMS coil”) that is positioned adjacent the head of a human patient. Each current pulse causes the TMS coil to produce an intense magnetic field. This magnetic field induces changes in the state of polarization of neurons in the patient's brain, which changes in turn evoke activity in the brain. Measurement of this activity makes it possible to e.g. determine the functions of particular brain regions and to form a functional map of the brain.
A TMS study of a patient is carried out in two steps. In the first step, the TMS coil is targeted to the brain region of interest. Once this targeting has been accomplished, the actual study of the brain region is carried out by directing a series of pulses to the targeted region.
Conventionally, these steps are carried out with the technician holding the TMS coil in position. This is problematic because the TMS coil and its attached cable weigh approximately 9 pounds (approximately 4 kilograms) and the technician is challenged to keep the TMS coil properly targeted, i.e. properly located on the patient's head and properly oriented towards the brain region of interest. Additionally, it can be difficult for the technician to maintain such proper location and orientation when the patient's head moves.
Holders for TMS coils are known. These fix the position of the TMS coil in space, thereby eliminating problems associated with technician fatigue. However, such devices do not address the problems caused by movement of the patient's head. Furthermore, such devices do not facilitate repositioning of the TMS coil on the patient's head.